This continuing research includes several intimately linked investigations following cardiac surgery which utilize the singular opportunity afforded us by the myocardial marker technology, which has been developed, validated, and applied in our laboratories for 10 years with NIH funding. Adult and pediatric patients with diverse types of acquired and congenital heart disease will be comprehensively studied on a serial basis during the first 48 hours early postoperatively in the ICU and periodically late postoperatively. Left and right ventricular instantaneous volumes, systolic mechanics (global and segmental), synergy, and diastolic dynamics beat-by-beat and cardiac bioenergetics will be measured (using the unique noninvasive capabilities of the myocardial marker methods) to provide, for the first time in intact man, precise measurements of serial LV and RV pressure-volume loops, 3-dimensional LV kinematics and cardiac motion, and interactions between electrical and mechanical properties of the myocardium. The myocardial marker technique is uniquely well suited to fill this clinical research void since it generated noninvasively exact quantitative measurements as frequently as necessary without hazard to the patient. This technical capability to perform these clinical physiologic studies does not exist elsewhere due to several unique physical and professional resources. The effects of specific treatments, whether they be modifications of surgical techniques (e.g., preservation of chordae tendineae during mitral valve replacement) or postoperative support maneuvers, will be examined in terms of LV and RV mechanics. The knowledge gained as a result of this research will yield new insights into and improved understanding of the fundamental pathophysiology of heart disease, basic cardiac physiology, and the exact effects of cardiac surgical procedures, newer (untested) operative techniques, and pharmacological, mechanical, and physiological therapeutic interventions. Such will provide the basis for more refined surgical methods and more intelligent medical management. Importantly, these studies will enhance our understanding of the pathogenesis and mechanisms of ventricular arrhythmias and, for the first time, 3-dimensional kinematics of normal and diseased human hearts. Reduced operative risk, greater functional benefit derived from operation, and more propitious long-term survival rates should accompany this new insight. The attendant new fundamental physiological knowledge generated should translate ultimately into improved treatment of all patients with heart disease.